Valve actuating assembly

ABSTRACT

An internal combustion engine valve actuating assembly in which a valve actuating lever is fulcrumed on telescopically associated piston and cylinder members jointly defining an expansible chamber for reception of pressurized fluid tending to relatively extend said members. The bearing or fulcrum of the lever is located between the opposite axial ends of the slidably interengaged areas or interface of the members to minimize the creation of torque and/or tilting forces by longitudinal thrust of the lever.

United States Patent [191 Kruger 1 Feb. 13,1973

[54] VALVE ACTUATING ASSENIBLY [75] Inventor: Hermann Kruger, Wolfsburg,Germany [73] Assignee: Volkswagenwerk Aktiengesellschaft [22] Filed:Dec. 11, 1970 [21] Appl. No.: 97,186

[30] Foreign Application Priority Data Dec. 13, 1969 Germany ..P 19 62631.4

[52] US. Cl ..123/90.43, l23/90.46

[51] Int. Cl. ..F01l l/l8, F011 H24 [58] Field of Search 1 23/90.43,90.46

[56] References Cited UNITED STATES PATENTS 3,314,404 4/1967 Thompson123/9043 3,137,283 6/1964 Sampietro l23/90.43 1,930,568 10/1933 Short123/9043 2,865,353 12/1958 Sampietro 123/9043 2,873,730 2/ 1959 Kilgore..123/90.43

Primary ExaminerAl Lawrence Smith Attorney-Watson, Cole, Grindle &Watson 5 7 ABSTRACT An intemal combustion engine valve actuatingassembly in which a valve actuating lever is fulcrumed on telescopicallyassociated piston and cylinder members jointly defining an expansiblechamber for reception of pressurized fluid tending to relatively extendsaid members. The bearing or fulcrum of the lever is located between theopposite axial ends of the slidably interengaged areas or interface ofthe members to minimize the creation of torque and/or tilting forces bylongitudinal thrust of the lever.

1 Claim, 4 Drawing Figures PATENTEDFEB13I975 3,716,03

FIG.1 PRIOR ART n IN V EN TOR SHEET 2 (IF 2 PATENTEDFEB13 I975 VALVEACTUATING ASSEMBLY The present invention relates to a valve actuatingassembly more especially for internal combustion engines, containing alever pivotally supported in a bearing for actuating the valves and avalve clearance resetting system associated therewith, having a cylinderreceiving a pressure medium and a piston telescopically associated withthe cylinder, the cylinder co-operating with the piston by means of asliding track defined by their interengaged telescoping position. Suchvalve assemblies are known in which a substantially existing orsubsequently occurring valve clearance is removed by use of hydraulicpressure for extending the pressureimpacted piston, movements of thepiston in reverse direction due to any external forces being preventedby providing a non-return valve.

As has been found in known assemblies of this kind, force componentstransmitted by the lever to the bearing may have an adverse effect,which act at right angles to the sliding track, i.e., which exert amoment on the piston and the cylinder. To remedy this a long slidingtrack has been provided.

An object of the invention is to minimize the serious disadvantage ofknown valve assemblies with valve clearance adjustments by locating thebearing of the lever on the valve clearanceresetting member so as toengage over the sliding track.

This simple measure which, as yet to be shown, also provides advantagesfrom a constructional point of view which ensures that no torques occurwithin the valve clearance resetting member which tend to tilt thepiston relative to the cylinder and relative to the sliding track. Thisadvantageous effect of the measure is based on the fact that theeffective lines of the force components, extending at right angles tothe direction of the relative movement between the piston and cylinder,always intersect the mutual sliding track or interface of the piston andcylinder, so that they are unable to cause any torque within theassembly.

The cylinder can be made stationary and the piston located slidinglytherein; the bearing for the lever then is formed by an extensionengaging around the free end of the cylinder and extending outsidethereof at least partially over the region of the piston. In thisembodiment the free end of the cylinder projects substantially into anannular groove formed in the piston and which,

in the region of the bearing for the lever, has to be provided with alarger outer diameter than they cylinder. A reverse arrangement is alsopossible; the piston is stationary and the cylinder mounted slidinglythereon. The bearing for the lever is then formed by a portion of thecylinder jacket extending over the region of the piston so that thecylinder moves relative to the stationary piston. The term piston" andcylinder" is not applied in accordance with the distinction between themovable part and the fixedly located part but, as the cylinder there isalways denoted the part which forms a chamber for the pressure medium.

It is convenient for the supply of pressure medium to be provided by apassage through the fixedly located piston, to save using flexiblepipes. The piston can be providedwith suitable bores which willgenerally extend over'the whole length of the piston, if the cylinder ispermitted to form a pressure medium-filled chamber at the end of thevalve resetting system remote from the fixing end of the piston.

At this point it is observed that it is self-evident that a valve, moreespecially a non-return valve, should be provided in the region of thepressure medium-filled chamber of the cylinder.

The embodiment described presents various constructional advantages,inasmuch as the valve clearance resetting system can be retained, evenwith a low overall height, below the lever bearing, as for example in acylinder head of an internal combustion engine, since the cylinder formsthe pressure mediumfilled chamber in contrast to known assemblies whereits end is remote from the fixing point. If this chamber is located atthe upper end of the valve clearance resetting system and a liquidpressure medium is used, then the cylinder is provided at this upper endwith apertures for gas emission. These apertures may simultaneouslyserve to cause a certain leakage flow of the liquid pressure medium.

The invention is not limited to the use of a hydraulic pressure mediumbut also permits the use of a gaseous or steam-like pressure medium.Generally, however, the characteristic of a liquid of beingsubstantially incompressible, will have a favorable effect in thisconnection.

In a valve assembly such as is described above the bearing for the leveris formed as a ball joint.

, 1 The invention will now be described further, by way of example, withreference to the accompanying drawings, in which:

FIG. I is a fragmentary cross-section through a conventional valveassembly;

, FIG. 2 is a fragmentary cross-section of a valve assembly, having avalve clearance resetting system constructed in accordance with theinvention;

FIG. 3 is a section showing the use of a valve 7 clearance resettingsystem with a rocker lever; and

FIG. 4 is a section showing an alternative constructo supply thepressure medium which is unable to escape due to the provision of anon-return valve formed by a ball 5, a compression spring 6 and a cap 7.The cap 7 is held down by a spring 8 which is of greater dimensions thanthe spring 6. The piston member 1 is provided with a bearing 9 at itsupper end which projects substantially out of the cylinder member 2, thebearing being formed as a ball joint for a lever 10, which is a rockeror trailing lever, angularly movable in the axial plane of thetelescopically associated members l and 2, by means (not shown) toactuate a valve.

As soon as the lever 10 transmitsa force component 1 to'the bearing 9and hence to the piston I which is directed at right angles to a commonsliding track 11 of piston l and cylinder 2 within the latter, a torqueis exerted on the cylinder member 2 which tends to axially tilt theupper end of the member 2 about its lower end. This has to becompensated by a counter torque. The appertaining forces 11 and III actin opposite directions on the outer surfaces of the piston I, so that atII a force acts on the outer surface which, because of the mechanicaladvantage attained through exertion of the force 1 against the axiallyprojecting bearing 9, is greater than the force I causing it. This atfirst becomes noticeable by a relatively high surface pressure in theupper region of the sliding track 11. Moreover, the torque caused by theforce 1 results in a varied stressing of the different areas of thesliding track 11, since it tends to tilt the piston member' 1 in thecylinder member 2. This in turn results in undesired local wearing ofthe sliding track 11.

In accordance with the present invention, these disadvantages areovercome by axially locating the bearing or pivotal connection betweenthe lever and said other member between the opposite axial ends of thesliding track.

In the embodiment of the invention, shown in FIG. 2, a rocker ortrailing lever 20 has a bifurcated or eyeletlike region engaging arounda valve clearance resetting system. The resetting system substantiallyconsists of a piston member 21, which moves inside a cylinder member 22,the piston member 21 being fixedly located at its end (shown at thebottom in the Figure) in a wall 23 of the cylinder head, whilst thecylinder member 22 of the system slides along a common sliding track 24defined by the common area of telescoping engagement between the members21 and 22.

The cylinder member 22 forms a pressure mediumfilled variable volumechamber 25 in the region of its upper end remote from the fixedlysupported lower e l/d of the piston member 21 and serves to receive anon return valve 28 of known type. The pressure mediun'i'is suppliedthrough the wall 23 of the cylinder head via a passage 26 which iscontinued in a passage 27 within the piston member 21. A ball 28, whichtogether withla compression spring 29 and a cap 30 having a passageaperture for pressure medium in its upper end, forms the non-returnvalve and is arranged in the upper e'nd of the passage 27. r

The cap 30 is held down by a spring 31. The bore 32 at the upper end ofthe cylinder serves as an outlet and also to ensure a small leakage flowof the pressure liquid used herein. The leakage flow may simultaneouslyact as lubrication for the bearing of the lever'fil), when suitablyarranged also to lubricate other sliding parts of the valve drive, suchas cam surfaces.

The cylinder member 22 has a spherical outerjacket portion 33 and soforms a bearing in the form of a ball joint for the lever 20. Thebearing 33 embraces the common sliding track 24 of piston 21 andcylinder 22, or in other words, is located between the opposite axialends of the sliding track 24 to minimize transmission of tilting forceson the member 22 by lever 20.

Since the bearing 33 can transmit force components only acting at rightangles on its surface and, moreover,

since these force components are directed in a line intersecting thecommon sliding track 24 between the ends thereof, the transverse forcecauses no moments tilting the cylinder member 22 relative to the pistonshaft 42 to a valve control system 43. Naturally, the

force exerted by the valve clearance resetting system has to be directedopposite the forces of 42 and 43 on the lever.

in the embodiment shown in FIG. 4 the known system of a piston membermovable within a stationary cylinder member, is retained, but modifiedin such a manner that again transverse forces are directed in a lineintersecting the common sliding track and consequently cannot exert anydisturbing torques. For this purpose a piston member 51 slidinglymounted within a stationary cylinder member 50 is specifically formed.

It engages with a collar-like extension 52, which may be formed by anadditional part connected to the piston member 51, around the free endof the cylinder member 50, so that this free end of the cylinder memberextends substantially into an annular groove 53 of the piston member,the outer diameter of which is larger than that of the cylinder member.Further details of the piston cylinder arrangement correspond to thoseof the embodiments already described and are not shown in detail. Theouter jacket surface of the extension 52 is constructed as a ball joint54 to function as a bearing for a lever 55, which in eyelet-like andbifurcated formation engages over this arrangement. The ball bearing 54is thus located in a region below which a common sliding surface 56 ofpiston member 51 and cylinder member 50 extends. This, in turn, ensuresthat no interfering torques can occur within the system owing totransverse forces transmitted from the lever 55 to the bearing.

While there are above disclosed but a limited number of embodiments ofthe invention, further embodiments will be obvious without departingfrom the inventive concept herein disclosed, and as defined in theappended claims.

Having thus described my invention, 1 claim:

1. Valve actuating assembly, especially for an internal combustionengine, comprising telescopically arranged piston and cylinder membersjointly defining a variable volume chamber into'which a fluid pressuremedium is supplied through a non-return valve;

said cylinder member being fixedly supported and said members havingportions slideably engaging each other to form a sliding track withinsaid cylinder member;

a lever extending transversely to the cylindrical axis of said members;

a bearing located axially on said piston member at least partly betweenthe opposite axial ends of such sliding track,

said bearing pivotally supporting said lever for rocking movement aboutsaid bearing in the plane of the cylindrical axis of said members toactuate a valve of the assembly, whereby to minimize tilting forces onsaid piston member arising from longitudinal thrust from said member toinstitute its rocking movement, said bearing being formed by anextension of said piston member engaging around the free end of saidcylinder and extending outside thereof and at least partly over thesliding track region of said piston and said cylinder members.

1. Valve actuating assembly, especially for an internal combustionengine, comprising telescopically arranged piston and cylinder membersjointly defining a variable volume chamber into which a fluid pressuremedium is supplied through a non-return valve; said cylinder memberbeing fixedly supported and said members having portions slideablyengaging each other to form a sliding track within said cylinder member;a lever extending transversely to the cylindrical axis of said members;a bearing located axially on said piston member at least partly betweenthe opposite axial ends of such sliding track, said bearing pivotallysupporting said lever for rocking movement about said bearing in theplane of the cylindrical axis of said members to actuate a valve of theassembly, whereby to minimize tilting forces on said piston memberarising from longitudinal thrust from said member to institute itsrocking movement, said bearing being formed by an extension of saidpiston member engaging around the free end of said cylinder andextending outside thereof and at least partly over the sliding trackregion of said piston and said cylinder members.